JP2003262482A - Heat transfer material and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat transfer material improving a heat transfer efficiency using phase change heat storage substance and reducing the power of a pump for transferring it. <P>SOLUTION: This heat transfer material is formed by adding the phase change heat storage substance 4 having a phase change temperature in a temperature range between a heat feeder side heat feed temperature and a heat use device side heat dissipation temperature and a polymer substance 6 for reducing a flow resistance, to aqueous liquid 2. The addition of the phase change heat storage substance changing its phase in a prescribed temperature range can absorb/dissipate large heat capacity via the heat transfer material. The addition of the polymer substance allows the whole fluid as the heat transfer material to show viscoelasticity and reduce the flow resistance. The polymer substance to be added is preferably polyethylene oxide. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat carrier material used for carrying cold heat and / or warm heat, and a heat carrier system using this heat carrier material.

[0002]

2. Description of the Related Art Heretofore, as a heat carrier for carrying cold heat and / or warm heat, there has been proposed one in which a phase change heat storage substance is stably dispersed in water as the heat carrier. The heat carrier is circulated between a heat supply device that supplies cold heat and / or warm heat and a heat use device that uses this heat, and the cold heat and / or warm heat supplied by the heat supply device is used as a heat use device. The phase change heat storage substance in the heat carrier material releases the cold heat and / or the warm heat that has accumulated due to the phase change in the temperature range between the heat supply temperature of the heat supply device and the heat release temperature of the heat utilization device. To do.

As a heat transfer material of this type, for example, a heat storage material such as tetradecane, pentadecane, paraffin wax, etc. is contained in a microcapsule made of melamine resin, polyurethane resin, polyacrylic resin, polymethacrylic acid resin or the like. It is known that the latent heat storage microcapsules (so-called phase change heat storage substance) are stably dispersed in water. Such a heat transfer method using a phase change heat storage material can store and transfer a large amount of heat energy in a narrow temperature range sandwiching the melting point, as compared with a heat transfer method using only sensible heat without phase change. As a result, there is an advantage that a large amount of heat can be conveyed with a small flow rate as compared with the case where only water is used as the heat carrier. A heat transfer method using such a phase change heat storage material is disclosed in, for example, Japanese Patent Laid-Open No. 5-117642.
Japanese Patent Laid-Open No. 5-163486, Japanese Laid-Open Patent Publication No. 5-2
It is proposed by Japanese Patent Publication No. 15369.

In preparing a dispersion liquid in which such latent heat storage microcapsules (phase change heat storage substance) are dispersed, for example, a heat storage material and a prepolymer of a melamine resin are both polymerized while being dispersed and emulsified in water. By forming a latent heat storage microcapsule having a structure in which a capsule outer layer made of a polymer coating is formed on the outer periphery of a core mainly composed of a heat storage material, and stably dispersing the latent heat storage microcapsule thus formed in water, The dispersion can be obtained.

[0005]

The latent heat storage microcapsule dispersion liquid, that is, the heat carrier material containing the phase change heat storage substance, has a viscosity of water because of the reason that the latent heat storage microcapsules are dispersed in the aqueous solution. Higher than itself,
The viscosity tends to increase as the concentration of the latent heat storage microcapsules added to water increases.

The fact that the viscosity of the dispersion liquid becomes large means that when the latent heat storage microcapsule dispersion liquid is used to transport the heat from the heat supply device to the heat utilization device (heat demand equipment) through the pipe, the pump is used. It means that the power of is increased. It is generally known that the power of a pump is proportional to the viscosity of the fluid to be fed to the power of 0.25. For example, the latent heat storage microcapsule dispersion has a viscosity of 1
If it becomes 0 times, the power of the pump becomes about 1.8 times that of water. In this way, when the latent heat storage microcapsule dispersion is used as the heat carrier medium, compared with the case of using water itself, the latent heat storage microcapsules utilize the latent heat,
Although it is possible to increase the heat transfer efficiency by increasing the heat density per unit volume, there is a problem that the power of the pump also increases.

In view of the above-mentioned facts, the object of the present invention is to improve the heat transfer efficiency by using the phase change heat storage substance and to reduce the power of the pump for transferring it. A material and heat transfer system.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the inventors of the present invention have made earnest studies and, as a result, added a polymer substance having a flow resistance reducing effect to an aqueous solution in which a phase change heat storage substance is dispersed. By doing so, it was found that the power of the pump for carrying the aqueous solution containing the phase change heat storage substance due to the high viscosity is remarkably reduced as compared with water, and the present invention has been completed.

Before describing the constitution and operation of the present invention, a polymer having a flow resistance reducing effect will be described. When a predetermined polymer substance is dissolved in water in the range of several tens to several hundreds ppm, a network of the polymer substances is formed. , It is said to exhibit viscoelasticity, and a method for reducing friction of a polymer solution having such characteristics is described in, for example, T. Mizushina et al, Journa.
l of Chemical Engineering of Japan, Vol. 7, No. 3,
162 (1974).

According to the present invention, in order to reduce the flow resistance of an aqueous liquid, a phase change heat storage substance having a phase change temperature in the temperature range between the heat supply temperature on the heat supply device side and the heat release temperature on the heat utilization device side. And a polymer substance of 1) are added.

The heat transfer material of the present invention is characterized in that it can be dispersed in a heat transfer fluid, and a heat storage part mainly composed of a phase change heat storage material that changes its phase in a predetermined temperature range, for example, a heat storage material made of an organic compound. A phase-change heat storage material (latent heat storage microcapsules) having a coating polymer layer to be dispersed is dispersed in an aqueous liquid such as water, and a polymer substance having a flow resistance reducing effect is further added to the dispersed aqueous solution. Especially. As a result, the heat storage material of the heat storage part of the phase change material stores heat while changing the phase, so that a large amount of heat can be absorbed and released via the heat transfer material, and the coating polymer of the phase change heat storage material allows It is possible to disperse the phase change heat storage substance substantially uniformly. In addition, since a polymer substance having a flow resistance reducing effect is added, even if the viscosity increases after the phase change heat storage substance is mixed with the aqueous liquid, the entire fluid as a heat carrier material exhibits viscoelasticity. Therefore, even if this heat carrier material is made to flow through a pipe or the like, its flow resistance is reduced, and as a result, it is possible to reduce the power of the pump for feeding the heat carrier material.

The polymer substance to be added is preferably polyethylene oxide, which can impart viscoelasticity to the entire fluid and reduce its flow resistance.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a heat carrier material according to the present invention. This heat carrier material contains an aqueous liquid 2 such as water as a main component, and the aqueous liquid 2 contains a phase change heat storage substance 4. The polymer substance 6 is stably dispersed. The phase change heat storage material 4 is
The organic compound 8 as a heat storage material accompanied by a phase change and a resinous coating material 10 constitute a minute latent heat storage microcapsule in which the organic compound 8 is housed in the resinous coating material 10.

Next, regarding the material of each component of the heat transfer material,
Further details will be described. Organic compounds as heat storage materials 8
Is a linear paraffin (aliphatic hydrocarbon) such as tetradecane, pentadecane, hexadecane, benzene, p-
An aromatic compound such as xylene, a linear carboxylic acid such as nonanoic acid or decanoic acid, or a mixture thereof, an organic compound such as an ester compound, or a mixture thereof are used.

The capsule material constituting the resin coating material 10 includes melamine resin, urea resin, phenol resin,
Condensation polymers such as nylon and acrylic polymers such as polystyrene and polymethylmethacrylate are used.

Further, the polymer substance 6 is not particularly limited, and polyethylene oxide, polymethylmethacrylate or the like is used. Further, as the aqueous liquid 2, the water described so far is used. In this case, ethylene glycol, propylene glycol, various inorganic salts, preservatives, various deterioration preventing agents, dispersion aids, specific gravity adjusting agents, wetting agents and the like may be added as necessary.

With respect to the amount of the polymer substance 6 added to the entire dispersion (heat carrier), if the amount is small, the flow resistance reducing effect will not be exhibited, and if it is too large, the viscosity will increase, which also has the flow resistance reducing effect. Does not develop. Therefore, the addition amount of the polymer substance 6 is preferably 1 to 500 ppm,
More preferably, it is 200 ppm.

Such a heat transfer material is used to transfer the heat (cold heat and / or warm heat) generated in the heat supply device (not shown) to the heat utilization device (not shown). It is circulated through a supply device, a heat utilization device, and a supply flow path and a return flow path (which are configured by pipes or the like) connecting these. And the phase change heat storage material 4 of the heat carrier material
Undergoes a phase change in the temperature range between the heat supply temperature on the heat supply device side and the heat release temperature on the heat utilization device side, and by this phase change, a large amount of heat energy can be absorbed and released.

Examples and Comparative Examples In order to confirm the effect of reducing the flow resistance of the heat transfer material of the present invention, the following flow resistance evaluation experiment was conducted. FIG. 2 is a diagram schematically showing a configuration of an evaluation device used in the flow resistance evaluation experiment. The evaluation device will be described with reference to FIG. It is provided with an exchanger 14 and a cold / hot water generator 15. The medium tank 11 is filled with the heat carrier material, and the pump 12
The heat transfer material in the medium tank 11 is circulated through the pipe 18 (which constitutes a flow path). The pipe 18 is made of vinyl chloride (V
It is a circular pipe made of P pipe and having a nominal diameter of 25A. Cold / hot water generator 1
5, hot and cold water is generated, the cold and hot water is circulated through the plate heat exchanger 14, and heat is exchanged between the cold and hot water and the heat transfer material in the heat exchanger 14. By this heat exchange, the heat transfer material is Is indirectly adjusted to a predetermined temperature. The temperature at which the heat transfer material flows through the pipe 18 is the platinum resistance temperature detector 16
It is possible to monitor the measured value. The flow resistance reduction effect was evaluated in relation to the pressure loss by the fine differential pressure gauge 17 installed in the differential pressure measurement section A (which is set to 2 m in this evaluation device) in the pipe 18. Further, an inverter is connected to the pump 12, and the electromagnetic flow meter 13 is set so that the heat transfer material flows at a predetermined flow rate through the pipe 18.

As Example 1, the following heat transfer material was used. First, 40 g of n-pentadecane and styrene 10
g and a polymerization initiator (2,2 azobis (2,4 dimethylvaleronitrile)) 0.8 g with stirring at room temperature for 5 minutes,
An organic compound mixture was prepared.

Next, the entire amount of the above-mentioned organic compound mixed liquid was added to 160 g of a 0.1% aqueous solution of polyvinyl alcohol to form an emulsion having a particle size of 3 to 5 μm. At this time, the polyvinyl alcohol aqueous solution was 8000 rp.
Add the organic compound mixture while stirring vigorously at m.
By adding with stirring, the organic compound mixture was emulsified. Then, this emulsion was kept under stirring conditions at 60 ° C. for 5 hours to promote the polymerization reaction of styrene. In this state, n-pentadecane and styrene are considered to be dispersed in the aqueous solution as a microcapsule body having a heat storage part made of n-pentadecane and a coating layer made of polystyrene.

The above synthetic procedure was repeated to prepare a total of 10 kg of microcapsule dispersion. Then, polyethylene oxide (average molecular weight: 3470) was added to this dispersion.
000) was added at 100 ppm, and this dispersion was used in Example 1
Was used as a heat carrier.

As Example 2, the following heat transfer material was used.
First, after adding 37 g formaldehyde aqueous solution 6.5 g and water 10 g to 5 g of melamine powder to adjust pH to 8,
By heating to about 70 ° C., a melamine-formaldehyde initial condensate was obtained. Next, 80 g of n-pentadecane as an organic compound accompanied by a phase change was added to 100 g of a 5% styrene-maleic anhydride copolymer sodium salt aqueous solution whose pH was adjusted to 4.5 with vigorous stirring. The emulsification was carried out until the particle size became 5 μm. Add all the melamine-formaldehyde initial condensate to the emulsion,
After stirring at 0 ° C. for 2 hours, the pH was adjusted to 9 and the encapsulation was completed.

The above synthetic operation was repeated to prepare a total of 10 kg of the dispersion liquid. And to this dispersion liquid, 100 parts of polyethylene oxide (average molecular weight: 3470000) was added.
ppm was added and this dispersion was used as the heat carrier in Example 2.

As Comparative Example 1, after synthesizing the microcapsule dispersion in Example 1, a dispersion was prepared under the same conditions except that polyethylene oxide was not added, and this dispersion was used as the heat carrier material of Comparative Example 1. Used as.

Further, as Comparative Example 2, after synthesizing the microcapsule dispersion liquid in Example 2, a dispersion liquid was prepared under the same conditions except that polyethylene oxide was not added, and this dispersion liquid was heated by the heat of Comparative Example 2. Used as a carrier.

The results of the flow resistance evaluation experiments for Examples 1 and 2 and Comparative Examples 1 and 2 are shown in FIG. FIG. 3 shows the relationship between the flow velocity of the heat transfer materials of Examples 1 and 2 and Comparative Examples 1 and 2 and the pressure loss per unit length at the flow velocity. The temperature of each heat transfer material in this flow resistance evaluation experiment was 7 ° C.

As is apparent from FIG. 3, Examples 1 and 2
The pressure loss of the heat transfer material of No. 2 is significantly lower than that of the heat transfer materials of Comparative Examples 1 and 2 under the same flow rate condition, and the flow resistance is significantly reduced by adding polyethylene oxide. It was confirmed that it was possible. Therefore, even when a microcapsule dispersion liquid (phase change heat storage substance dispersion liquid) having a heat density higher than that of water is used as a heat carrier, it is possible to improve the flow resistance by adding a polymer substance that reduces the flow resistance. It can be seen that the heat carrier can be pumped with less power energy without increasing it.

Further, using the above-mentioned flow resistance evaluation device,
In the heat carrier material of Example 1, the pressure loss when the addition concentration of polyethylene oxide to be added was changed was examined. In this evaluation experiment, the flow velocity of the heat carrier is 1.5 m.
/ S. The evaluation result is as shown in FIG. 4, which shows the relationship between the concentration of polyethylene oxide added to the microcapsule dispersion and the pressure loss per unit length. As shown in FIG. 4, it was found that the pressure loss can be reduced by about 70% by adding a trace amount of polyethylene oxide of several ppm to several hundred ppm.

[0030]

According to the heat carrier material of the present invention and the heat carrier system using this heat carrier material, since the phase change heat storage member and the polymer substance are added to the aqueous liquid, the heat carrier material is used. A large amount of heat can be absorbed and released, and the entire fluid as a heat carrier can be made viscoelastic to reduce its flow resistance. As a result, the power of the pump for feeding the heat carrier can be reduced. Can be reduced.

[Brief description of drawings]

FIG. 1 is a simplified diagram conceptually showing an example of a heat carrier of the present invention.

FIG. 2 is a schematic diagram conceptually showing a flow resistance evaluation apparatus used in a flow resistance evaluation experiment.

FIG. 3 is a diagram showing a relationship between flow velocities of various heat transfer materials and pressure loss per unit length.

FIG. 4 is a diagram showing the relationship between the concentration of a polymer substance added to a heat transfer material and the pressure loss per unit length.

[Explanation of symbols]

2 Aqueous liquid 4 Phase change heat storage material 6 Polymer 8 organic compounds 10 Resin coating material

Claims (3)

[Claims] 1. A phase change heat storage material having a phase change temperature in an aqueous liquid in a temperature range between a heat supply temperature on the heat supply unit side and a heat release temperature on the heat utilization unit side, and a high temperature change material for reducing flow resistance. A heat carrier which is characterized in that a molecular substance is added. 2. The heat carrier according to claim 1, wherein the polymer substance is polyethylene oxide. 3. A heat transfer system using the heat transfer material according to claim 1.